Abstract

High-Frequency (HF) radars are operated in the HF band of the radio wave
spectrum, i.e.\ between 5 MHz and 30 MHz. Due to the physics involved, these
radars are able to look behind the horizon. Signals backscattered from
the ocean's surface contain information about currents, ocean wave spectra
and wind. Depending on the radar frequency, working ranges up to 150 km
can be achieved. As for optimum performance, these radars should be installed
at the shore, the term 'Coastal Radar' is often used in this context.
Combining HF radar remote sensed data with high-resolution numerical
models by data assimilation brings together the advantages of both
technologies: The HF radar can provide accurate forcing and boundary
conditions to the model and keep the model nowcast 'close to nature',
the model can than be used to supply high quality forecasts. For
highly variable oceanographic processes, such as mesoscale eddies
and fronts, this approach might be the only way to provide reliable
now- and forecasts. This leads to a better understanding of the
dynamics of coastal processes.
The operational forecasting system described above has been set-up
and tested within the EU funded project EuroROSE. Comparisons of
an HF radar aided model to a free running model showed an increase
in correlation for the 4-hour forecast from 0.27 to 0.77 due to
data assimilation.
klaus-werner.gurgel@uni-hamburg.de last update 05-APR-2005